41 lines
1.8 KiB
Swift
41 lines
1.8 KiB
Swift
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import Foundation
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import CoreGraphics
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/// Places district labels so their boxes don't overlap. Each district starts at
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/// a hash-derived seed; if its (padded) label box collides with an already-placed
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/// one, we spiral outward — rotating and pushing away from downtown — until we
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/// find clear space. Existing placements never move, so the map stays stable as
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/// new districts appear.
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///
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/// Pure and deterministic given its inputs; no SpriteKit, fully unit-testable.
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public enum LayoutSolver {
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/// - Parameters:
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/// - baseAngle/baseRadius: the hash-derived seed in polar coords.
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/// - localRect: the label box *relative to the node center* (labels sit
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/// below the dot, so this is usually offset downward).
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/// - existing: already-placed label boxes in world space.
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/// - pad: minimum gap to keep between boxes.
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/// - Returns: a world-space center for the new district.
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public static func placeNonOverlapping(
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baseAngle: Double,
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baseRadius: Double,
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localRect: CGRect,
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existing: [CGRect],
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pad: CGFloat = 16,
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maxAttempts: Int = 400
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) -> CGPoint {
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for attempt in 0..<maxAttempts {
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let angle = baseAngle + Double(attempt) * 0.45 // rotate as we go
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let radius = baseRadius + Double(attempt) * 7 // and push outward
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let center = CGPoint(x: cos(angle) * radius, y: sin(angle) * radius)
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let box = localRect.offsetBy(dx: center.x, dy: center.y).insetBy(dx: -pad, dy: -pad)
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if !existing.contains(where: { $0.intersects(box) }) {
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return center
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}
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}
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// Give up gracefully at the seed (extremely crowded map).
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return CGPoint(x: cos(baseAngle) * baseRadius, y: sin(baseAngle) * baseRadius)
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}
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}
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